Double-y-shaped multi-lumen catheter with selectively attachable hubs

ABSTRACT

A multi-lumen catheter and method for inserting same in a patient is disclosed. The catheter includes an elongated, central, multi-lumen tube portion having a proximal end and a distal end. The central tube portion has a substantially cylindrical outer shape and is internally segmented into a plurality of lumens. A distal branch portion includes a plurality of single-lumen distal extension tubes. A proximal branch portion includes a plurality of single-lumen proximal extension tubes. Each proximal extension tube has a distal first end and a proximal second end. The distal first end of each proximal extension tube is connected to the proximal end of the central tube portion such that the single lumen of each distal extension tube is in fluid communication with one of the plurality of lumens of the central tube portion. Each lumen of the central tube portion and the lumens of the distal and proximal extension tubes in fluid communication therewith define a flow path through the catheter. Selectively attachable hub connectors are provided for selective attachment to the distal extension tubes and connection of the catheter to a fluid exchange device.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/086,033, filed Feb. 28, 2002, now U.S. Pat. No. 6,638,242,which is a continuation of U.S. patent application Ser. No. 09/769,052,filed Jan. 24, 2001, abandoned.

BACKGROUND

1. Field of the Invention

The present invention relates generally to medical instruments and morespecifically to a multi-lumen catheter including y-shaped distal andproximal ends, and including selectively attachable hubs for selectivelyconnecting the catheter to a fluid exchange device.

2. Description of the Prior Art

Catheters, generally, are hollow, flexible tubes for insertion into abody cavity, duct, or vessel to allow the passage of fluids or distend apassageway. Catheters are often used for temporary or long-term dialysistreatment. Dialysis treatment provides for blood to be withdrawn fromthe patient, purified, and then returned to the patient. Thus, indialysis treatment, catheters are used to allow passage of a patient'sblood into and out of the patient's body. For optimal performance duringdialysis treatment, the catheter tips, both in-flow and out-flow, shouldbe placed in close proximity to the heart. Typically, medical personneluse either a double lumen catheter or two single lumen catheters. Bothtypes, however, present certain deficiencies.

While double lumen catheters (e.g., U.S. Pat. No. 4,895,561) allow for asingle insertion of the catheter into the desired vein, double lumencatheters typically do not permit optimal catheter tip placement. Due todifferences among patients, optimal top position varies from patient topatient. Non-optimal tip position may significantly lower flow values,resulting in less effective dialysis treatment. For current double lumencatheters, a physician must make an estimate regarding the appropriatecatheter tube length prior to beginning the procedure ofcatheterization. Then, a subcutaneous tunnel is made from a first end,which is near the area to be catheterized, to a second end, which is thepreferred end position of the hub assembly, namely, away from the neckof the patient, in order to allow for more convenient access to thedialysis treatment equipment. The catheter tube is then routed forwardlythrough the subcutaneous tunnel from the second end to the first end sothat the catheter tips extend outwardly from the first end of thetunnel. Either before or after tunneling, a sheath is inserted throughthe first end of the tunnel and into the area to be catheterized, andthe catheter tips are inserted into the sheath and the area to becatheterized. The estimated catheter tube length and subsequent forwardtunneling may result in less than optimal tip placement.

With the use of two independent single lumen catheters (e.g., U.S. Pat.No. 5,776,111 to Tesio) the problem of tip placement is addressed. Thehub assembly of each catheter is removable from the tube and tip portionof the catheter, thereby allowing the catheter tip to be placed directlyinto the vein and advanced into the desired position. Then, the proximalend of the catheter can be reverse tunneled and trimmed to a desiredlength. Thereafter, the hub assembly is attached. Deficiencies, however,exist in this method of catheterization as well. One problem associatedwith this method is that this method requires two separate venousinsertions, namely, two tunnels and two of each accessory instrumentused for the procedure. Therefore, there is increased surgical timerequired to place two catheters, there are two wound entry sites whichdoubles the risk of post-surgical infection, and the two catheterstogether are significantly larger in diameter than one double lumencatheter.

Applicant's co-pending applications Ser. No. 09/769,052 filed Jan. 24,2001, and Ser. No. 10/086,033, filed Feb. 28, 2002, disclose amulti-lumen catheter apparatus an method for inserting the apparatus ina patient. The disclosures of these co-pending applications are herebyincorporated by reference. In the disclosed apparatus and method, amulti-lumen catheter includes a selectively attachable hub assembly thatallows the catheter tip to be positioned accurately within a patient'svein prior to subcutaneous tunneling. The distal end of the cathetertube is selectively attachable to the hub assembly. Accordingly, afterthe tips of the catheter have been accurately positioned in a patient,the other end of the catheter may be reverse tunneled under the skin ofa patient. Before or after tip placement, an incision is made in theskin adjacent to the point where the protruding distal end of thecatheter exits the skin. A subcutaneous tunnel is then formed having afirst end at the incision and a second end exiting the skin at a pointremote from the first end of the tunnel, generally as the caudaldirection. A sheath dilator is inserted into the tunnel, which ispartially dilated so as to accommodate a tissue in-growth stabilizingcuff. The distal end of the catheter tube is routed through thesubcutaneous tunnel and the cuff seated therein, thereby stabilizing thedistal portion of the catheter tube in the patient. A selectivelyattachable hub assembly is connected to the lumens at the distal tip ofthe catheter tube for subsequent connection of the catheter to a fluidexchange device, such as a dialysis machine.

While the selectively attachable hub assembly described abovefacilitates tunneling a multi-lumen catheter in a patient, the separablehub assembly creates the need to connect the hub to a distal end of amulti-lumen catheter tube, thereby adding an additional step to thecatheter insertion/connection procedure, which increases surgical timeand expense. Furthermore, the hub-catheter connection provides anadditional connection which may leak or separate from the catheter tubedue to external loads on the hub such as by pulling or snagging. Inaddition, the attachable hub assembly is a relatively complex part,which makes it difficult to manufacture and, therefore, use of the hubassembly increases the cost of the catheter itself.

Therefore, there is a need for multi-lumen catheter that can be insertedinto a patient using a reverse tunneling technique, which permitsaccurate placement of the tips of the catheter into the area to becatheterized and that is selectively attachable to a fluid exchangedevice. The improved catheter should not require an extensive hubassembly, thus making it relatively inexpensive to manufacture and easyto insert into a patient.

SUMMARY OF THE INVENTION

A multi-lumen catheter is provided for use in hemodialysis and the like.The multi-lumen catheter includes an elongated, central, multi-lumentube portion having a distal end and a proximal end. The central tubeportion has a substantially cylindrical outer shape and is internallysegmented into a plurality of lumens. A distal branch portion includes aplurality of single-lumen distal extension tubes. Each distal extensiontube has a proximal first end and a distal second end. The proximalfirst end of each distal extension tube is connected to the distal endof the central tube portion such that the single lumen of each distalextension tube is in fluid communication with one of the plurality oflumens of the central tube portion. A proximal branch portion includes aplurality of single-lumen proximal extension tubes. Each proximalextension tubes has a distal first end and a proximal second end. Thedistal first end of each proximal extension tube is connected to theproximal end of the central tube portion such that the single lumen ofeach distal extension tube is in fluid communication with one of theplurality of lumens of the central tube portion. A plurality ofselectively attachable connector hubs are provided, each connector hubbeing configured to be selectively attachable to the distal second endof one of the distal extensions and being configured for selectiveconnection to a fluid exchange device. Each lumen of the central tubeportion and the lumens of the distal and proximal extension tubes influid communication therewith define a flow path through the catheter.An in-growth stabilizing cuff may be affixed to an outer portion of thecentral tube portion.

The multi-lumen catheter may include a central tube portion having twolumens. In such a catheter, the distal branch portion includes twodistal extension tubes, and the proximal branch portion includes twoproximal extension tubes. The catheter may be arranged such that theplurality of single-lumen distal extension tubes of the distal branchportion converge to form a distal multi-lumen connecting portion whichconnects to the distal end of the central tube portion, and theplurality of single-lumen proximal extension tubes comprising theproximal branch portion converge to form a proximal multi-lumenconnecting portion which connects to the proximal end of the centraltube portion.

The central tube portion, the distal extension tubes, and the proximalextension tubes may be comprised of a fusible material, and the distalextension tubes and proximal extension tubes may be respectively fusedto the distal and proximal ends of the central tube portion. The distalextension tubes may have a substantially cylindrical outer shape neartheir distal second ends, and the proximal multi-lumen connectionportion may also have substantially cylindrical outer shape. Theproximal extension tubes may have a substantially D-shaped cross-sectionover at least a portion of their length. Also, the proximal extensiontubes may be substantially parallel to each other in a free state, andthe proximal second ends of the distal extension tubes may belongitudinally spaced from each other.

The multi-lumen catheter may further include a plurality of connectorhubs for connecting the catheter to a fluid exchange device. Eachconnector hub may configured to be connected to the distal second end ofone of the distal extension tubes, and configured for connection to aportion of a fluid exchange device. Each of the proximal extension tubesmay include a tube wall, and each of the proximal extension tubes mayinclude at least one opening extending through its tube wall. Further,an external portion of at least one of the distal extension tubes mayinclude indicia which indicates a discrete flow path through thecatheter. In one arrangement, the two proximal extension tubes havelongitudinal axes which intersect at an included angle in a free state,the included angle being in a range from about 10 degrees to about 30degrees.

A y-shaped catheter junction for a multi-lumen catheter is alsoprovided. The y-shaped junction includes a dual-lumen trunk, having asubstantially cylindrical outer wall, a first end, a second end, a firstlumen, and a second lumen. A first single-lumen extension tube isconnected to the first end of the trunk, such that the single lumen ofthe first single-lumen extension tube is in fluid communication with thefirst lumen of the trunk. A second single-lumen extension tube isconnected to the first end of the trunk such that the single lumen ofthe second single-lumen extension tube is in fluid communication withthe second lumen of the trunk. The y-shaped junction is arranged suchthat the first lumen of the trunk and the first extension tube define afirst flow path, and the second lumen of the trunk and the secondextension tube define a second flow path. The y-shaped catheter junctionmay also be arranged such that the first and second extension tubes havelongitudinal axes which intersect at an included angle near the firstend of the trunk in a free state, the included angle being in a rangefrom about 10 degrees to about 30 degrees.

A method of forming a multi-lumen catheter is also disclosed. The methodincludes attaching a first plurality of single-lumen extension tubes toa distal end of a length of multi-lumen tubing comprising a plurality ofmultiple lumens, and attaching a second plurality of single-lumenextension tubes to a distal end of the length of multi-lumen tubing.Each single lumen of each extension tube is in fluid communication withone of the lumens of the length of multi-lumen tubing. The length ofmulti-lumen tubing may include two lumens, and the first and secondpluralities of extension tubes may form substantially y-shaped junctionson each end of the length of multi-lumen tubing.

The method of forming a multi-lumen catheter may include first forming ay-shaped distal junction. The process may include providing a firstlength of single-lumen tubing to form a distal arterial extension tube,providing a second length of single-lumen tubing to form a distal veinalextension tube, providing a first length of multi-lumen tubingcomprising at least an arterial lumen and a veinal lumen, and having adistal end and a proximal end, attaching an end of the distal arterialextension tube to the distal end of the first length of multi-lumentubing such that the distal arterial extension tube is in fluidcommunication with the arterial lumen of the first length of multi-lumentubing, and attaching an end of the distal veinal extension tube to thedistal end of the first length of multi-lumen tubing such that thedistal veinal extension tube is in fluid communication with the veinallumen of the first length of multi-lumen tubing. The proximal end of thefirst length of multi-lumen tubing forms a connecting end.

A second length of multi-length tubing having a distal end and aproximal end is provided. The tubing includes an arterial lumen and aveinal lumen. The connecting end of the first length of multi-lengthtubing is connected to the distal end of the second length ofmulti-length tubing, such that the arterial extension tube of the distaljunction in fluid communication with the arterial lumen of the secondlength of multi-lumen tubing, and the veinal extension tube of thedistal junction is in fluid communication with the veinal lumen of thesecond length of multi-lumen tubing.

A y-shaped proximal junction is also formed. This process includesproviding a third length of single-lumen tubing to form a proximalarterial extension tube, and providing a fourth length of single-lumentubing to form a proximal veinal extension tube. A third length ofmulti-lumen tubing is also provided which includes at least an arteriallumen and a veinal lumen, and has a distal end and a proximal end. Anend of the proximal arterial extension tube is attached to the distalend of the third length of multi-lumen tubing such that the proximalarterial extension tube is in fluid communication with the arteriallumen of the third length of multi-lumen tubing, Also, an end of theproximal veinal extension tube is attached to the distal end of thethird length of multi-lumen tubing such that the proximal veinalextension tube is in fluid communication with the veinal lumen of thethird length of multi-lumen tubing. The distal end of the third lengthof multi-length tubing forms an attachment end.

The attachment end of the third length of multi-length tubing isattached to the proximal end of the second length of multi-lumen tubing,such that the arterial extension tube of the proximal junction is influid communication with the arterial lumen of the second length ofmulti-lumen tubing, and the veinal extension tube of the proximaljunction is in fluid communication with the veinal lumen of the secondlength of multi-lumen tubing. The method may also include forming atleast one opening in a wall of the proximal veinal extension tube, andforming at least one opening in a wall of the arterial proximalextension tube. The steps of attaching extension tubes and lengths ofmulti-lumen tubing together or to each other may include heat welding orsimilar fusing techniques. The longitudinal axes of the distal arterialextension tube and distal veinal extension may be arranged to intersectat an included angle in a free state in a range from about 10 degrees toabout 30 degrees.

A method for surgically implanting a double-Y-shaped multi-lumencatheter into a patient is also provided. The method is suited forimplanting a multi-lumen catheter having an elongated, central,multi-lumen tube portion, a proximal end portion including asingle-lumen proximal veinal extension tube and a single-lumen proximalarterial extension tube each having a proximal tip, and a distal endportion including a single-lumen distal veinal extension tube and asingle-lumen distal arterial extension tube each having a distal end.The method includes making an incision in the skin of the patient, andinserting the proximal tips of the proximal veinal and arterialextension tubes through the incision and placing the proximal tips inthe patient. A subcutaneous tunnel is formed having a first endproximate to the incision and second end remote from the first end ofthe tunnel. The distal veinal and arterial extension tubes and at leasta portion of the central tube portion are guided through thesubcutaneous tunnel such that at least the distal ends of the distalveinal and arterial extension tubes extend outwardly from the tunnelthrough the second end of the tunnel. At least a portion of the distalend portion of the catheter is secured to the patient such as by suturesor any other suitable means.

When the catheter includes a stabilizing cuff, the method may furtherinclude dilating at least a portion of the subcutaneous tunnel toreceive the cuff. Dilation of the tunnel may be accomplished by slidinga sheath dilator along the shaft of a trocar longitudinally positionedwithin the tunnel. The distal end portion of the catheter is secured tothe patient by seating the cuff in a dilated portion of the subcutaneoustunnel.

The catheter implanting method may further include respectivelyconnecting the distal arterial and veinal extension tubes to arterialand veinal legs of a fluid exchange device. Connecting the distalarterial and veinal extension tubes may include connecting the distalarterial extension tube to the arterial leg with a first connector hub,and connecting the proximal veinal extension tubes to the veinal legwith a second connector hub. Inserting the proximal tips of the proximalveinal and arterial extension tubes into a patient may include placingthe proximal tip of the veinal extension tube into a vein in thepatient, and placing the proximal tip of the arterial extension tubeinto an artery in the patient.

These and other aspects of the invention will be made clear from areading the following detailed description together with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a double y-shaped multi-lumen catheter;

FIG. 2 is a cross-sectional view of a distal portion of the multi-lumencatheter of FIG. 1;

FIG. 3 is a partially exploded detail perspective view of a distalportion of the multi-lumen catheter of FIG. 1;

FIG. 4 is a partially exploded detail perspective view of a proximalportion of the multi-lumen catheter of FIG. 1;

FIG. 5 is a cross-sectional view of a proximal portion of themulti-lumen catheter of FIG. 1;

FIGS. 6A-6D illustrate a procedure for tunneling a multi-lumen catheterlike that of FIG. 1 in a patient;

FIG. 7 is a partial sectional view of a sheath dilator engaged along atrocar to dilate a portion of a subcutaneous tunnel in a patient;

FIGS. 8A-8C are views of a connection between a distal end of thecatheter and a trocar for guiding the catheter through a subcutaneoustunnel.

DETAILED DESCRIPTION

For the purposes of the following description and the claims appendedhereto, the relative term “proximal” refers to those portions of acatheter and those portions of components of the catheter which arenearest the insertion end of the catheter, that is, the end of thecatheter that is inserted into an area of a patient'as body beingcatheterized, such as a blood vessel. Conversely, the relative term“distal” refers to those portions of a catheter and those portions ofcomponents of the catheter which are farthest from the insertion end ofthe catheter.

FIG. 1 shows a double-Y-shaped multi-lumen catheter 10 according to thepresent invention. The catheter 10 includes a proximal end 34 forinsertion into a patient, and a distal end 36 for connection to a fluidexchange device, such as a dialysis machine or the like. The catheter 10includes an elongated, central, multi-lumen tube portion 12, a pluralityof proximal single-lumen extension tubes 14, 16, and a plurality ofdistal single-lumen extension tubes 18, 20. In the embodiment shown, thecentral tube portion 12 includes an arterial lumen 5 and a veinal lumen6. In this arrangement, the catheter 10 includes a proximal veinalextension tube 14 and a distal veinal extension tube 18 in fluidcommunication with the veinal lumen 6, and a proximal arterial extensiontube 16 and a distal arterial extension tube in fluid communication withthe arterial lumen 5. The catheter 10 may include a stabilizing cuff 15affixed to an outer portion of the central tube portion 12 as shown inFIG. 1. Preferably, the cuff 15 is longitudinally positioned on thecentral tube portion 12 such that the cuff 15 will be finally positionedin a subcutaneous tunnel in a patient as described more fully below.

A construction for the distal end 36 of the multi-lumen catheter 10 isshown in FIGS. 1-3. As shown in FIGS. 2 and 3, the proximal ends 18 p,20 p of the distal extension tubes 18, 20 may be connected to a distalend 12 d of the central tube portion 12 by a distal multi-lumen trunk30. The multiple lumens of the distal trunk 30 correspond in number tothe multiple lumens of the central tube portion 12 and the number ofdistal extension tubes 18, 20. In the illustrated embodiment, the distaltrunk 30 includes a veinal distal trunk lumen 48, and an arterial distaltrunk lumen 47 as shown in FIG. 2. As shown in FIG. 3, the proximal ends18 p, 20 p of the distal extension tubes 18, 20 are connected to thedistal end 30 d of the distal trunk, thereby forming a substantiallyY-shaped junction. The proximal end 30 p of the distal trunk 30 isconnected to the distal end 12 d of the central tube portion 12 as shownin FIG. 2, thereby forming a Y-shaped distal end 36. Preferably, theproximal end 30 p of the distal trunk 30 is substantially cylindrical inshape, and is substantially equal in outer diameter to the outerdiameter of the central tube portion 12, thereby providing a smoothtransition at the juncture between the distal trunk 30 and the centraltube portion 12.

As shown in FIG. 2, the distal extension tubes are arranged such that anincluded angle “θ” exists between the longitudinal axes of the tubes 18,20 in a free state. In a preferred arrangement, the angle “θ” rangesfrom about 10 degrees to about 30 degrees. The distal extension tubes18, 20 can be arranged, however, so that the angle “θ” is any desiredangle. The veinal distal trunk lumen 48 is in fluid communication withthe veinal lumen 6 of the central tube portion 12 and the single lumenof the distal extension tube 18. Similarly, the arterial distal trunklumen 47 is in fluid communication with the arterial lumen 5 of thecentral tube portion 12 and the single lumen of the distal arterialextension tube 20.

In an alternative arrangement, the distal extension tubes 18, 20 may beconnected directly to the distal end 12 d of the central tube portion 12rather than to an interconnected distal trunk 30 (not shown). In eitherarrangement, the mating end portions of the distal extension tubes 18,20, the distal end of the central tube portion 12 d, and/or the distaltrunk 30 are sealably fused together by heat welding or the like suchthat the fluid communication between the interconnecting lumens of thecomponents is established and maintained and no leakage occurs at theconnections.

As shown in FIGS. 1-3, the catheter 10 also includes selectivelyattachable connector hubs 72, 74 on the distal ends 18 d, 20 d of thedistal extension tubes 18, 20. As will be described in detail below, theconnector hubs 72, 74 are selectively attachable so that the connectorhubs 72, 74 can be attached to and removed from the distal end 36 of thecatheter 10 after insertion of the proximal end 34 of the catheter 10into a patient, and after reverse, subcutaneous tunneling of the distalend 36. As shown in FIGS. 1 and 2, the connector hubs 72, 74 areconfigured for selectively sealable attachment between the distal ends18 d, 20 d of the distal extension tubes 18, 20 and legs of a fluidexchange device. The connector hubs. The veinal connector hub 72 isselectively attached to the distal portion 18 d of the distal veinalextension tube 18, and the arterial connector hub 74 is selectivelyattachable to the distal portion 20 d, of the distal arterial extensiontube 20.

In one embodiment as shown in FIGS. 1-3, the selectively attachable hubs72, 74 are connectable with mating compression fittings 58, 60. Thecompression fittings may include cannulae 66, 68 and threaded maleportions 62, 64 that matingly engage the distal extension tubes 18, 20and the connector hubs 72, 74 as shown in FIG. 2. When fully engaged,the hubs 72, 74 and compression fittings 58, 60 compress compressionsleeves 70 about the distal portions 18 d, 20 d of the distal extensiontubes 18, 20, thereby forming sealed connections. The compressionfittings 58, 60 may be further connected to luer-type fittings 50, 52,or the like by connector tubes 54, 56. The luer-type fittings 50, 52 maythen be connected to corresponding luer-type connection mechanisms on afluid exchange device 200. For example, the distal ends of the luer-typefittings 50, 52 may include quarter-turn type threads for leak-tightengagement with matching quarter-turn fittings on the veinal andarterial legs of a fluid exchange device 200. Other types of knowleak-tight selectively attachable connection configurations may also beused.

As shown in FIGS. 1 and 3, the connector hubs 72, 74 can be selectivelyattached to the distal ends 18 d, 20 d of the distal extension tubes 18,20. This arrangement permits the distal end 36 of the catheter 10 to besubcutaneously reverse tunneled in a patient as described more fullybelow without interference from the hubs 72, 74. After the distal end ofthe catheter 10 is subcutaneously reverse tunneled in a patient suchthat the distal end 36 protrudes outwardly from the patient, the hubs72, 74 can be backfit over the distal ends of distal extension tubes 18,20 as shown for hub 72 in FIG. 3. The compression sleeves 70 can then beplaced over the distal ends 18 d, 20 d of the extension tubes 18, 20,and the sealed connections can be completed as shown in FIG. 2. Thecatheter 10 can then be connected to a fluid exchange device 200.

A construction for the proximal end 34 of the catheter 10 is shown inFIGS. 1, 4, and 5. The distal ends 14 d, 16 d of the proximal extensiontubes 14, 16 may be connected to a proximal end 12 p of the central tubeportion 12 by a proximal multi-lumen trunk 32. The lumens of theproximal trunk 32 correspond in number to the multiple lumens of thecentral tube portion 12 and to the number of proximal extension tubes14, 16. In the illustrated embodiment, the proximal trunk 32 includes aveinal proximal trunk lumen 31, and an arterial proximal trunk lumen 33as shown in FIG. 5. As shown in FIG. 4, the distal ends 14 d, 16 d ofthe proximal extension tubes 14, 16 are connected to the proximal end 32p of the proximal trunk 32, thereby forming a substantially Y-shapedjunction. The distal end 32 d of the proximal trunk 32 is connected tothe proximal end 12 p of the central tube portion 12 as shown in FIG. 5,thereby forming a substantially Y-shaped proximal end 34 on the catheter10. Preferably, the distal end 32 d of the proximal trunk 32 issubstantially cylindrical in shape, and is substantially equal in outerdiameter to the outer diameter of the central tube portion 12, therebyproviding a smooth transition at the juncture between the proximal trunk32 and the central tube portion 12.

As shown in FIG. 5, the proximal extension tubes are arranged such thatan included angle “α” exists between the longitudinal axes of the tubes14, 16 in a free state. In a preferred arrangement, the angle “α” isabout 5 degrees in a rest position or free state. The proximal extensiontubes 14, 16 can be arranged, however, so that the angle “α” is anydesired angle. The veinal proximal trunk lumen 31 is in fluidcommunication with the veinal lumen 6 of the central tube portion 12 andthe single lumen of the proximal veinal extension tube 14. Similarly,the arterial proximal trunk lumen 33 is in fluid communication with thearterial lumen 5 of the central tube portion 12 and the single lumen ofthe proximal arterial extension tube 16.

In an alternative arrangement, the proximal extension tubes 14, 16 maybe connected directly to the proximal end 12 p of the central tubeportion 12 rather than to an interconnecting proximal trunk 32 (notshown). In either arrangement, the mating end portions of the proximalextension tubes 14, 16, the proximal end of the central tube portion 12p, and/or the proximal trunk 32 are sealably fused together, such as byheat welding or the like, such that the fluid communication between theinterconnected lumens of the components is established and maintainedand no leakage occurs at the connections.

As shown in FIGS. 1, 4, and 5, the proximal arterial extension tube 16is preferably shorter in length than the proximal veinal extension tube14. For example, the proximal arterial extension tube 16 may be about 4cm shorter in length than the proximal veinal extension tube 14. Theresulting longitudinal spacing between the proximal tips 14 p and 16 pfacilitates optimal proximal tip placement in a patient. As shown inFIG. 4, the proximal veinal extension tube 14 may include an end opening43 in or near its proximal tip 14 p. The proximal veinal extension tube14 may also include one or more transverse openings 42 in its tube wall40. Similarly, as also shown in FIG. 4, the proximal arterial extensiontube 16 may include an end opening 47 in or near its proximal tip 16 p.The proximal arterial extension tube 16 may also include one or moretransverse openings 46 in its tube wall 44. The openings 42, 43, 46, and47 facilitate fluid flow into or out from the proximal extension tubes14, 16.

The hubs 72 and 74 are selectively attachable and detachable from thedistal end 36 of the catheter 10 to facilitate tunneling the catheter 10in a patient. A method of installing a catheter 10 in a patient isillustrated in FIGS. 6A-6D. As shown in FIG. 6A, an incision 100 is madein the skin of a patient. The proximal tips 14 p, 16 p of catheter 10are inserted through the incision 100 and are placed at desiredlocations within the patient using conventional techniques, such as theSeldinger technique.

At this stage, the distal end 36 and distal portions of the catheter 10extend outwardly from the incision 100. A trocar 120 or other suitableinstrument is used to form a subcutaneous tunnel 102 having a first end104, which is preferably coincident with the incision 100, and anopposed second end 106, which is remote from the first end 104, as shownin FIG. 6A.

As shown in FIG. 6B, the distal end 36 of the catheter 10 is insertedthrough the first end 104 of the tunnel 102, and the distal end 36 isguided through the tunnel 102 such that the distal end 36 extends outfrom the tunnel 102 at its second end 106. The distal extension tubes18, 20 are sufficiently flexible that they may be bundled or clampedtogether by any suitable means to facilitate passing the Y-shaped distalend 36 of the catheter 10 through the tunnel 102.

In a preferred arrangement as shown in FIGS. 8A and 8B, the distal ends18 d, 20 d of the distal extension tubes 18, 20 are attached to aconnector 300. The proximal end of the connector 300 may include a firsttip 302 and a second tip 304 as shown. The tips 302, 304 are insertableinto the lumens at the distal ends 18 d, 20 d of the distal extensiontubes 18, 20. The tips 302, 304 preferably include ribs 301 or the liketo tightly engage within the distal ends 18 d, 20 d of the distalextension tubes 18, 20 such that the connector 300 is securely butremovably attached to the extension tubes 18, 20. When the tips 302, 304are respectively engaged in the distal extension tubes 18, 20, theconnector 300 holds the distal extension tubes 18, 20 in closearrangement as shown so that the distal extension tubes 18, 20 can besimultaneously subcutaneously tunneled in a patient as described below.The distal end of the connector 300 d preferably includes a bore 306which is configured to attachably receive an insertion tip 308 of thetrocar 120. The bore 306 may include threads 310 which can be engagedwith mating threads 312 on the insertion tip 308 of the trocar 120.Alternatively, the bore 306 may include a collar portion 314 which snapsinto a groove 309 on the insertion tip 308 of the trocar 120 as shown inFIG. 8C. In this way, the distal end 300 d of the connector 300 can beengaged on the insertion tip 308 of the trocar 120 to route the attacheddistal extension tubes 18, 20 through the subcutaneous tunnel 102 withthe trocar 120. Once the distal end 36 of the catheter 10 has been drawnthrough the tunnel 102, the connector 300 can be disengaged from thedistal extension tubes 18, 20.

In order to provide the distal portions of the catheter 10 with a smoothand compact outer profile to facilitate passage of the distal end 36 ofthe catheter 10 through the tunnel 102, a sheath 320 may be used asshown in FIG. 8B. The sheath 320 is placed over at least a portion ofthe connector 300 and the distal extension tubes 18, 20. Preferably, thedistal end 320 d of the sheath 320 is tapered as shown. The sheath 320and the distal portions of the catheter 10 can be drawn together throughthe tunnel 102 with the trocar 120. The sheath 320 is removed from thecatheter 10 once the distal portions of the catheter 10 have been drawnthrough the tunnel 102.

As shown in FIG. 6C, the distal end 36 of the catheter 10 is drawn fromthe second end 106 of the tunnel 102 such that the distal extensiontubes 18, 20 and at least a portion of the central tube portion 12extends from the second end 106 and the catheter 10 is fully tunneled inthe patient. The incision 100 and the second end 106 of the tunnel aresuitably treated and dressed.

An outer portion of the central tube portion 12 may include a tissuein-growth stabilizing cuff 15, as shown in FIG. 1, for stabilizing theinserted catheter 10 in the patient. Referring to FIGS. 6C and 7, whenthe catheter 10 includes a stabilizing cuff 15, a portion 130 of tunnel102 may be dilated to enlarge the width of the tunnel 102 to receive thecuff 15 as the catheter 10 is drawn through the tunnel 102. As shown inFIG. 7, the dilated portion 130 of the tunnel is preferably dilated bysliding a sheath dilator 200 over an end 42 and shaft 41 of the trocar120 when the trocar 120 is positioned in the subcutaneous tunnel 102 asshown in FIG. 6A. The sheath dilator 200 preferably includes a hollowbore 208, a tapered leading end 206, a substantially cylindrical portion204, and a handle 202. The sheath dilator 200 is inserted through thefirst end 104 of the tunnel 102 and into the tunnel 102 until the tip206 has been inserted proximate to a cuff seating point 140 in thetunnel 102 to form a dilated portion 130 of the tunnel 102. Once thedilated portion 130 is sufficiently dilated, the sheath dilator 200 isremoved from the tunnel 102 and the trocar 120. The catheter 10 isfinally positioned in the tunnel 120 when the cuff 15 is seated near anend 140 of the dilated portion 130 of the tunnel 102 as shown in FIG.6C.

As shown in FIG. 6D, the catheter 10 is connected to a fluid exchangedevice 200. The distal end 18 d of the distal veinal extension tube 18is selectively attached to a veinal leg 228 of the fluid exchange device200 by connector hub 72. Similarly, the distal end 20 d of the distalarterial extension tube 20 is selectively attached to an arterial leg222 of the fluid exchange device 200 by connector hub 74. As shown inFIG. 3, indicia 26 and 28 may be included on the distal extension tubes18, 20 and/or the connector hubs 72, 74 to assist medical personnel inidentifying the proper distal extension tube 18 or 20 for connection toa corresponding leg of the fluid exchange device 200. The indicia 26, 28may be markings, colors, or any other distinctive indicator.

While this invention has been illustrated and described in accordancewith a preferred embodiment, it is recognized that variations andchanges may be made therein without departing from the invention as setforth in the claims. Certain modifications and improvements will occurto those skilled in the art upon a reading of the forgoing description.For example, while the multi-lumen catheter has been described withreference to a catheter with two lumens, the invention also includesmulti-lumen catheters including three or more lumens as required. Itshould be understood that all such modifications are not containedherein for the sake of conciseness and readability, but are properlywithin the scope of the following claims.

1. A method for surgically implanting a double-Y-shaped multi-lumencatheter tube into a patient, the multi-lumen catheter including anelongated, central, multi-lumen tube portion, a proximal end portionincluding a single-lumen proximal veinal extension tube and asingle-lumen proximal arterial extension tube each having a proximaltip, and a distal end portion including a single-lumen distal veinalextension tube and a single-lumen distal arterial extension tube eachhaving a distal end, the method comprising: (a) making an incision inthe skin of the patient; (b) inserting the proximal tips of the proximalveinal and arterial extension tubes through the incision and placing theproximal tips in the patient; (c) forming a subcutaneous tunnel having afirst end proximate to the incision and a second end remote from thefirst end of the tunnel; (d) guiding the distal veinal and arterialextension tubes and at least a portion of the central tube portionthrough the subcutaneous tunnel such that at least the distal ends ofthe distal veinal and arterial extension tubes extend outwardly from thetunnel through the second end of the tunnel; and (e) securing at least aportion of the distal end portion of the catheter to the patient.
 2. Amethod according to claim 1, the method further comprising respectivelyconnecting the distal arterial and veinal extension tubes to arterialand veinal legs of a fluid exchange device.
 3. A method according toclaim 2, wherein connecting the distal arterial and veinal extensiontubes to arterial and veinal legs of a fluid exchange device comprisesconnecting the distal arterial extension tube to the arterial leg with afirst connector hub, and connecting the proximal veinal extension tubesto the veinal leg with a second connector hub.
 4. A method of claim 1,wherein inserting the proximal tips of the proximal veinal and arterialextension tubes into a patient comprises: placing the proximal tip ofthe veinal extension tube into a vein in the patent; and placing theproximal tip of the arterial extension tube into an artery in thepatient.
 5. The method of claim 1 wherein the central tube portionfurther includes a stabilizing cuff affixed to an outer portion of thecentral tube portion, the method further comprising dilating at least aportion of the subcutaneous tunnel before guiding the distal veinal andarterial extension tubes and at least a portion of the central tubeportion through the subcutaneous tunnel, wherein the dilating stepcomprises sliding a sheath dilator along a shaft of a trocarlongitudinally positioned in the tunnel.
 6. The method of claim 5wherein securing at least a portion of the distal end portion of thecatheter to the patient comprises seating the stabilizing cuff in adilated portion of the subcutaneous tunnel.
 7. The method of claim 1wherein guiding the distal veinal and arterial extension tubes and atleast a portion of the central tube portion through the subcutaneoustunnel comprises: (a) inserting a trocar through the subcutaneous tunnelsuch that an insertion tip of the trocar protrudes from the first end ofthe tunnel; (b) connecting the distal ends of the distal veinal andarterial extension tubes to a proximal end of a connector; (c)connecting a proximal end of the connector to the protruding insertiontip of the trocar; and (d) guiding the distal veinal and arterialextension tubes and at least a portion of the central tube portionthrough the subcutaneous tunnel with the trocar.
 8. The method of claim7 further comprising placing a sheath having a smooth outer contour overthe connector and at least portions of the veinal and arterial extensiontubes before guiding the distal veinal and arterial extension tubes andat least a portion of the central tube portion through the subcutaneouswith the trocar.